A butterfly wall plug, often called a butterfly anchor or expansion anchor, is a type of fastening hardware used to secure objects to walls, particularly in hollow materials like drywall or plaster. When the anchor is inserted into the wall, its wings expand once the screw is tightened, providing a strong hold.

Here are some key points about butterfly wall plugs:

1. Use: Ideal for hanging heavier objects such as shelves, mirrors, or artwork.
2. Installation: Requires a hole to be drilled into the wall, after which the butterfly anchor is inserted and expanded.
3. Weight Capacity: They offer a good weight capacity depending on the material of the wall and size of the anchor.
4. Removal: Can be difficult to remove without damaging the wall, as the wings may remain inside.